GATE | GATE-CS-2015 (Set 3) | Question 54

Given the function F = P′ + QR, where F is a function in three Boolean variables P, Q and R and P′ = !P, consider the following statements.

  S1: F = Σ (4, 5, 6)
  S2: F = Σ (0, 1, 2, 3, 7)
  S3: F = Π (4, 5, 6)
  S4: F = Π (0, 1, 2, 3, 7) 

Which of the following is true?
(A) S1-False, S2-True, S3-True, S4-False
(B) S1-True, S2-False, S3-False, S4-True
(C) S1-False, S2-False, S3-True, S4-True
(D) S1-True, S2-True, S3-False, S4-False


Answer: (A)

Explanation: After drawing K map of F = P` + QR ,we can find out S2 and S3 are TRUE.

Alternate Explanation :

P Q R = (!P + QR)

0 => 0 0 0 => 1+0.0 =1 =>Σ

1 => 0 0 1 => 1+0.1 =1 =>Σ

2 => 0 1 0 => 1+1.0 =1 =>Σ

3 => 0 1 1 => 1+1.1 =1 =>Σ

4 => 1 0 0 => 0+0.0=0 =>Π

5 => 1 0 1 => 0+0.1=0 =>Π

6 => 1 1 0 => 0+1.0=0 =>Π

7 => 1 1 1 => 0+1.1=1 =>Σ

as sigma means 1 and pi means 0
therefore Σ = (0,1,2,3,7)
Π = (4,5,6)

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